Process of manufacturing isoprene.



- iTED STATES PATENT oFEIoE.

WILLIAM HENRY- PERKIN AND CHARLES WEIZMANN, o MANoHEs'rER, ENGLAND,

ASSIGNORS 'I'Q RESEARCH SYNDICATE LIMITED, 0F LoNDoN, ENGLAND.

PROCESS OF MANUFACTURING ISOPRENE.

No Drawing.

Specification of Letters Patent.

Patented May 2, 1911.

provements in the Process of Manufacturing Isoprene, of which thefollowing is a specification.

This invention relates to a process of producing isoprene which may beused as an intermediate product in the manufacture of caoutchouc.

. According to this invention, either of the following fouramyl=alcohols, or amixture of two, or more, of them, is treated, ashereinafter described, for the production of isoprene, which can becondensed and polymerized for the production of caoutchouc. Theamyl-alcohols referred to are the following derivatives of isopentane,viz.:

The derivative selected, or a mixture of two, or more, of the saidderivatives, is, by dehydration, converted into one, or more, of theamylenes 2- on, CH3 on..- on, CH; 015

or: c or: on $13 211a (in (11H a 6H3 iHa This dehydration can beefi'ected in any suitable manner, such, for instance, as by the actionof zinc chlorid, the reaction being accelerated by heat. Either of thesaid amylenes is then treated sothat it loses two.

atoms of hydrogen and isoprene is produced. This is effected, in thecase of one, or more, of the amylenes, by the action of heat and can bedone by passing the amylene through a tube heated ,to dull redness, orby treatment of one, or more, of the amylenes, with bromin, or chlorin,forming a dihalogen derivative and subsequently removing two molecularproportions of hydrogen bromid, or hydrogen chlorid.

The followin is an example of how this invention may e performed but theinven tion is not limited .to this example. Two parts by weight ofordinary fermentation amylic alcohol are mixed with one part by weightof zinc chlorid and the mixture is allowed to stand in the cold fortwenty-four hours and is then distilled, the zinc chlorid removing onemolecular proportion of water from the amylic alcohol and yieldingamylene. This amylene is then passed through a tube heated to rednessand loses two atoms of hydrogen and isoprene is produced. This isoprenemay be then converted into caoutchouc by condensation andpolymerization.

In the above example instead of passing the amylenethrough a heatedtube, to convert it to isoprene, it can be treated with chlorin, orbromin, or both, and the halogen compound obtained be treated with anagent (such as diethyl-anilin, alcoholic potash, or sodium ethylate)which will combine with the hydrobromic acid and convert the saidcompound into isoprene.

Having now particularly described and ascertained the nature of our saidinvention, andin what manner the same is to be performed, we declarethat what we claim is 1. The process of producing isoprene whichcomprises dehydrating alcoholic derivatives of isopentane and thenremoving hydrdgen from the resulting amylenes, substantially asdescribed.

2.- The. process of producing isoprene which comprises dehydrating anayml alcohol derived from isopentaneand then removing hydrogen from theresulting amylene, substantially as described. 3

3. The ,process of producing isoprene which comprises dehydrating, with.zinc

chlorid, alcohol derivatives of isopentane and then removing hydrogenfrom the resulting amylenes, substantially as described. 4. The procesof producing isoprene which comprises llehydrating an amyl alco- 2 t I I991,453

hol derived from isopentane and then re- In testimony whereof we havesigned our 10 moving two atoms of hydrogen from the renames to thisspecification in the presence sulting amylene. of two subscribingwitnesses.

5. The process of producing isoprene 5 which comprises dehydratingalcoholic de- WILLIAM HENRY PERKIN" rivatives of isopentane and thenremoving CHARLES E hydrogen from the resulting amylenes, by Witnesses:

' passing the latter through a heated tube, ERNEST ROWLEY,

substantially as described. JOHN MATHIEsON.

